Translation guide
The English word "doubtful" can express uncertainty about facts, suspicion about people or situations, or low probability. This guide helps learners choose natural Japanese expressions for each nuance.
Expressing that you are not sure whether something is true or will happen.
The most direct equivalent for "doubtful" in the sense of questionable or uncertain. Often used for facts, statements, or outcomes.
That story is a bit doubtful.
Pattern for "it is doubtful whether..."
Often means "suspicious" but can also mean "doubtful" or "unreliable" for information or weather. More colloquial than 疑わしい.
Literally "it is questionable." Used when you have doubts about the validity or truth of something.
The success of that plan is doubtful.
Formal/literary expression meaning "not certain" or "unclear." Used for facts or memories.
The truth of that rumor is doubtful.
Expressing that someone or something seems dishonest or not to be trusted.
The go-to word for "suspicious" or "doubtful" in the sense of seeming dishonest or shady. Can describe people, behavior, or situations.
Expressing that something is not likely to happen or be true.
Common way to say "unlikely" or "doubtful" for events. Literally "doesn't seem like it will happen."
Expressing personal doubt or lack of conviction about what to do or believe.
Literally "half-believing, half-doubting." Used when you are not fully convinced.
疑わしい is more about factual doubt or questionable truth, while 怪しい leans toward suspicion of dishonesty or shadiness. 怪しい is more common in everyday speech for people and situations.
His testimony is doubtful (questionable truth).
It's doubtful that he'll agree.
It's doubtful whether he will come on time.
It's doubtful whether he really did it.
明日の天気は怪しい。
Tomorrow's weather is doubtful.
That information is a bit doubtful, isn't it?
That person looks doubtful/suspicious.
Doubtful transactions are taking place.
Stronger than 怪しい, implies something smells fishy or is clearly dubious. Colloquial.
His excuse is doubtful/suspect.
Can also be used for suspicious character, but slightly more formal and less common in casual speech than 怪しい.
His behavior is doubtful.
Literally "cannot be trusted." Direct way to say someone or something is doubtful in terms of reliability.
That source is doubtful/untrustworthy.
It's doubtful that he will come.
It's doubtful that it will rain.
Literally "the possibility is low." More formal and objective.
The chances of success are doubtful.
Means "prospects are dim" or "unlikely." Often used for hopes or expectations.
His chances of recovery are doubtful.
I was doubtful about that story.
To feel doubtful/questionable about something. Verb phrase.
I felt doubtful about his explanation.
Literally "cannot have confidence." Expresses personal doubt.
I'm doubtful whether that's correct.
That man is suspicious/doubtful.
When describing a person as "doubtful" in the sense of suspicious, 怪しい is much more natural. 疑わしい人 sounds like "a person who is doubted" rather than "a suspicious person."
The weather looks doubtful.
I'm doubtful about his story.